The invention relates to a tool for chamfering and deburring end face tooth edges of spur and helical gears.
A tool for chamfering and deburring is known from the company brochure xe2x80x9cGleason-HURTH Rotary Deburring Toolsxe2x80x9d. In the case of gear wheels produced by a cutting operation a burr is formed on the end face tooth edges which must be removed for various reasons. Such a burr is an obstruction because in the subsequent working steps a plane surface, for example, the end face of the gear wheel, is designated to serve as a clamping or reference surface. A special risk for the toothing is a hardened burr which, at the latest during running within the gear, will break off and can damage the tooth flanks. Aside from the fact that a remaining burr also presents a risk for injury when handling the workpieces. For these reasons, already for a long time, numerous methods and devices have been used for removing the burr.
However, it is usually not sufficient to remove only the burrs. During hardening, for example, there is the risk that the pointed edge becomes glass-hard as a result of excessive carburization and will then break off under load. Therefore, the end face tooth edge must be provided additionally with a chamfer. Moreover, it protects the active tooth surface against damage. This goal is achieved with the device of the aforementioned kind in that material of the workpiece on the edge between the tooth flank and the end face is displaced in order to generate a single-flank or double-flank chamfer. This plastic deformation causes the material of the workpiece to be displaced by the rolling deburring wheel to the end face and into the tooth flank so that a so-called secondary burr results. This secondary burr has been removed in the past by means of a cutter at the end face and by means of a toothed smoothing wheel meshing with the workpiece. In the prior art, this smoothing wheel was a component independent of the driving wheel fixedly connected to the rolling deburring wheel or wheels. Already known from the aforementioned company brochure is also a tool of the aforementioned kind in which the spacer wheel fixedly connected with the rolling deburring wheel or wheels takes over the function of the driving wheel as well as the function of the smoothing wheel. This could also be referred to as a combined driving and smoothing wheel.
In order to obtain optimal smoothing results in wet and dry processing by means of the peripheral area of the spacer wheel functioning as the smoothing wheel, the helix angle of the toothing of the smoothing area must match exactly that of the workpiece. When this prerequisite is not fulfilled, then burr deformations are produced in the tooth flanks of the workpiece which during a subsequent hard fine machining cause a premature wear of the fine machining tool. However, according to practical experience, the helix angle of the workpieces to be machined changes constantly for reasons which include the following:
1. Different behavior of the materials during hardening.
2. Different hardening furnaces are used.
3. Manufacturing tolerances during hobbing.
Since the user of the tools of the aforementioned kind has no other possibility on site than to change the center distance in the deburring machine, this approach is usually selected. However, this approach is wrong. When reducing the axle spacing the material on the workpiece is compressed such that a material removal for a subsequent hard fine machining is made very difficult. This means also a premature wear of the tool. When, however, the center distance is increased, the burr deformation will grow correspondingly.
It is an object of the invention to further develop the tool of the aforementioned kind such that an adaptation to variations of the helix angles of the workpieces to be machined is made possible.
In the present invention, the spacer wheel is divided into at least two discs which are connected to one another so as to be adjustable rotationally relative to one another. The configuration according to the invention of the tool enables the user to react immediately to variations of the helix angle on the workpiece. For this purpose, the relative position of the two discs is changed such that the teeth arranged in the smoothing area will contact properly the tooth flanks of the workpiece and remove the secondary burr present thereat. Since each one of the two discs machines only one of the two edges of each tooth flank of the workpiece, the hollow grinding of the flank lines required for a single-part smoothing wheel can be omitted.
The two discs of the tool according to the invention are preferably displaced in the circumferential direction relative to one another such that the area which serves as a smoothing wheel of the one disc is positioned opposite the area of the other disc serving as a driving wheel. This ensures a much more quiet running during machining. Moreover, the smoothing and deburring result of each planar side can be adjusted in a targeted way. Also, the chamfer widths and the helix angle of the smoothing area can be optimized independently from one another.
In an especially advantageous embodiment of the tool according to the invention, it is provided that one disc has two threaded bores which are displaced in the circumferential direction, that the other disc has two bores which have a different angular spacing relative to one another than the threaded bores and partially overlap them, and that adjusting screws with a conical face end are screwed into the threaded bores of the one disc in such a way that the conical face ends contact the edges of the bores of the other disc only within in a partial area. By tightening one screw and correspondingly unscrewing the other screw, a relative rotation of the two discs of the tool in one direction can be achieved.